1. Field
Example embodiments may relate to focusing devices that may adjust focus of optical microscopes using laser scanning. Example embodiments may relate to focusing devices that may automatically adjust focus of optical microscopes using laser scanning.
2. Description of Related Art
A semiconductor device is manufactured by repeatedly performing unit processes such as deposition, photolithography, etching, cleaning, testing, etc., on a surface of a wafer made of a semiconductor material such as silicon. Recently, there is a demand for high integration and high performance of the semiconductor device. To this end, individual semiconductor-manufacturing unit processes must be developed to enable a semiconductor device to have a fine feature size and high performance while maintaining a yield of the semiconductor device.
One factor to reduce the yield of the semiconductor device may be wafer defects. For example, the defects may include scratches and/or particles formed at a thin film on the wafer, excessively-removed portions or non-removed portions of the thin film on the wafer, and/or pitting formed at the surface of the wafer, or the like. In particular, as the integration of the semiconductor device becomes higher, even micro-defects may lead to a serious malfunction of the semiconductor device, which otherwise and previously, may not adversely affect an operation or function of the semiconductor device. For this reason, there exists a need not only to reduce the defects formed in manufacturing the semiconductor device, but also to rapidly and accurately measure and test the defects formed on/at the wafer at a test process after each of the unit processes has been finished.
Image information acquired by an optical microscope, etc., may be used to detect the defects formed in manufacturing the semiconductor device or flat panel display (FPD). The image information must have a high magnification and high resolution in order to improve the accuracy of the defect detection. It may be important to acquire clear image information of a pattern of a substrate (for example, the wafer or liquid crystal display (LCD) panel) by accurately detecting a focal point of the optical microscope. Moreover, a fast focus detection and/or adjustment may be required to be suitable for a fast test process.